P20.10-A001-79
Example shown on engine 264 |
1 | Electric coolant pump |
Overview
This document contains information on:
Task
Function
Task
The electric coolant pump ensures needs-based circulation of the coolant in the following cooling circuits:
High-temperature circuit
Medium-temperature circuit
Low-temperature circuit
The electric coolant pump is located on the combustion engine next to the charge air cooler.
Function
Conventional mechanically driven coolant pumps are integrated either in the toothed belt or poly-V-belt drive. One crucial disadvantage is that the coolant pump is firmly coupled to the engine speed due to the gear ratio between the crankshaft drive gear and coolant pump impeller.
This results in high coolant throughput, e. g. when driving on the freeway, but low throughput when demand is high in the city or in stop-and-go traffic.
Conversely, electrically driven coolant pumps are operated independently of the engine rpm. The cooling output is adapted to the cooling requirements. As a result, the operating temperature is achieved faster and kept constant.
The electric coolant pump that is used is a centrifugal pump driven by a brushless electric motor. The electrical coolant pump can be operated by an electronic control upon request.
Due to their better efficiency, electric coolant pumps also help to save fuel.
The electrical coolant pump is actuated by the combustion engine control unit. When this occurs, it is regulated after the following signals have been evaluated:
Coolant temperature
Heater request
Engine speed
Engine torque
At a coolant temperature under 75 °C, the electrical coolant pump is deactivated unless a request occurs in the electrical coolant pump.
The operating temperature of the electric coolant pump is between -40 °C and 150 °C ambient temperature (for max. 30 minutes), 120 °C for continuous operation. The coolant temperature should lie between -10°C and a maximum of 125°C.
If the coolant pump loses communication, an integrated limp-home mode also ensures sufficient engine cooling in the event of malfunction.